Staging: IIO: Periodic timer based trigger

The original posting of this driver led to a discussion in
which it was commented that a better system was needed
for dealing with the many possible periodic interrupt
sources available on some SoCs.  Unfortunately that is
a big task and as far as I know, no-one has taken it
on as yet.  So in the meantime this driver is still
in here.
Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/iio/Kconfig

@@ -37,8 +37,11 @@ config IIO_TRIGGER
 	  ring buffers.  The triggers are effectively a 'capture
 	  data now' interrupt.
 
+
 source "drivers/staging/iio/accel/Kconfig"
 source "drivers/staging/iio/adc/Kconfig"
 source "drivers/staging/iio/light/Kconfig"
 
+source "drivers/staging/iio/trigger/Kconfig"
+
 endif # IIO

drivers/staging/iio/Makefile

@@ -11,4 +11,6 @@ obj-$(CONFIG_IIO_SW_RING) += ring_sw.o
 
 obj-y += accel/
 obj-y += adc/
-obj-y += light/
\ No newline at end of file
+obj-y += light/
+
+obj-y += trigger/
\ No newline at end of file

drivers/staging/iio/trigger/Kconfig

+#
+# Industrial I/O standalone triggers
+#
+comment "Triggers - standalone"
+
+if IIO_TRIGGER
+
+config IIO_PERIODIC_RTC_TRIGGER
+	tristate "Periodic RTC triggers"
+	depends on RTC_CLASS
+	help
+	    Provides support for using periodic capable real time
+	    clocks as IIO triggers.
+
+endif # IIO_TRIGGER

drivers/staging/iio/trigger/Makefile

+#
+# Makefile for triggers not associated with iio-devices
+#
+obj-$(CONFIG_IIO_PERIODIC_RTC_TRIGGER) += iio-trig-periodic-rtc.o
+

drivers/staging/iio/trigger/iio-trig-periodic-rtc.c

+/* The industrial I/O periodic RTC trigger driver
+ *
+ * Copyright (c) 2008 Jonathan Cameron
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * This is a heavily rewritten version of the periodic timer system in
+ * earlier version of industrialio.  It supplies the same functionality
+ * but via a trigger rather than a specific periodic timer system.
+ */
+
+#include <linux/platform_device.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/rtc.h>
+#include "../iio.h"
+#include "../trigger.h"
+
+LIST_HEAD(iio_prtc_trigger_list);
+DEFINE_MUTEX(iio_prtc_trigger_list_lock);
+
+struct iio_prtc_trigger_info {
+	struct rtc_device *rtc;
+	int frequency;
+	char *name;
+	struct rtc_task task;
+};
+
+static int iio_trig_periodic_rtc_set_state(struct iio_trigger *trig, bool state)
+{
+	struct iio_prtc_trigger_info *trig_info = trig->private_data;
+	if (trig_info->frequency == 0)
+		return -EINVAL;
+	printk(KERN_INFO "trigger frequency is %d\n", trig_info->frequency);
+	return rtc_irq_set_state(trig_info->rtc, &trig_info->task, state);
+}
+
+static ssize_t iio_trig_periodic_read_freq(struct device *dev,
+					   struct device_attribute *attr,
+					   char *buf)
+{
+	struct iio_trigger *trig = dev_get_drvdata(dev);
+	struct iio_prtc_trigger_info *trig_info = trig->private_data;
+	return sprintf(buf, "%u\n", trig_info->frequency);
+}
+
+static ssize_t iio_trig_periodic_write_freq(struct device *dev,
+					    struct device_attribute *attr,
+					    const char *buf,
+					    size_t len)
+{
+	struct iio_trigger *trig = dev_get_drvdata(dev);
+	struct iio_prtc_trigger_info *trig_info = trig->private_data;
+	unsigned long val;
+	int ret;
+
+	ret = strict_strtoul(buf, 10, &val);
+	if (ret)
+		goto error_ret;
+
+	ret = rtc_irq_set_freq(trig_info->rtc, &trig_info->task, val);
+	if (ret)
+		goto error_ret;
+
+	trig_info->frequency = val;
+
+	return len;
+
+error_ret:
+	return ret;
+}
+
+static ssize_t iio_trig_periodic_read_name(struct device *dev,
+					   struct device_attribute *attr,
+					   char *buf)
+{
+	struct iio_trigger *trig = dev_get_drvdata(dev);
+	struct iio_prtc_trigger_info *trig_info = trig->private_data;
+	return sprintf(buf, "%s\n", trig_info->name);
+}
+
+DEVICE_ATTR(name, S_IRUGO,
+	    iio_trig_periodic_read_name,
+	    NULL);
+DEVICE_ATTR(frequency, S_IRUGO | S_IWUSR,
+	    iio_trig_periodic_read_freq,
+	    iio_trig_periodic_write_freq);
+
+static struct attribute *iio_trig_prtc_attrs[] = {
+	&dev_attr_frequency.attr,
+	&dev_attr_name.attr,
+	NULL,
+};
+static const struct attribute_group iio_trig_prtc_attr_group = {
+	.attrs = iio_trig_prtc_attrs,
+};
+
+static void iio_prtc_trigger_poll(void *private_data)
+{
+	iio_trigger_poll(private_data);
+}
+
+static int iio_trig_periodic_rtc_probe(struct platform_device *dev)
+{
+	char **pdata = dev->dev.platform_data;
+	struct iio_prtc_trigger_info *trig_info;
+	struct iio_trigger *trig, *trig2;
+
+	int i, ret;
+
+	for (i = 0;; i++) {
+		if (pdata[i] == NULL)
+			break;
+		trig = iio_allocate_trigger();
+		if (!trig) {
+			ret = -ENOMEM;
+			goto error_free_completed_registrations;
+		}
+		list_add(&trig->alloc_list, &iio_prtc_trigger_list);
+
+		trig_info = kzalloc(sizeof(*trig_info), GFP_KERNEL);
+		if (!trig_info) {
+			ret = -ENOMEM;
+			goto error_put_trigger_and_remove_from_list;
+		}
+		trig->private_data = trig_info;
+		trig->owner = THIS_MODULE;
+		trig->set_trigger_state = &iio_trig_periodic_rtc_set_state;
+		trig->name = kmalloc(IIO_TRIGGER_NAME_LENGTH, GFP_KERNEL);
+		if (trig->name == NULL) {
+			ret = -ENOMEM;
+			goto error_free_trig_info;
+		}
+		snprintf((char *)trig->name,
+			 IIO_TRIGGER_NAME_LENGTH,
+			 "periodic%s",
+			 pdata[i]);
+		trig_info->name = (char *)trig->name;
+		/* RTC access */
+		trig_info->rtc
+			= rtc_class_open(pdata[i]);
+		if (trig_info->rtc == NULL) {
+			ret = -EINVAL;
+			goto error_free_name;
+		}
+		trig_info->task.func = iio_prtc_trigger_poll;
+		trig_info->task.private_data = trig;
+		ret = rtc_irq_register(trig_info->rtc, &trig_info->task);
+		if (ret)
+			goto error_close_rtc;
+		trig->control_attrs = &iio_trig_prtc_attr_group;
+		ret = iio_trigger_register(trig);
+		if (ret)
+			goto error_unregister_rtc_irq;
+	}
+	return 0;
+error_unregister_rtc_irq:
+	rtc_irq_unregister(trig_info->rtc, &trig_info->task);
+error_close_rtc:
+	rtc_class_close(trig_info->rtc);
+error_free_name:
+	kfree(trig->name);
+error_free_trig_info:
+	kfree(trig_info);
+error_put_trigger_and_remove_from_list:
+	list_del(&trig->alloc_list);
+	iio_put_trigger(trig);
+error_free_completed_registrations:
+	list_for_each_entry_safe(trig,
+				 trig2,
+				 &iio_prtc_trigger_list,
+				 alloc_list) {
+		trig_info = trig->private_data;
+		rtc_irq_unregister(trig_info->rtc, &trig_info->task);
+		rtc_class_close(trig_info->rtc);
+		kfree(trig->name);
+		kfree(trig_info);
+		iio_trigger_unregister(trig);
+	}
+	return ret;
+}
+
+static int iio_trig_periodic_rtc_remove(struct platform_device *dev)
+{
+	struct iio_trigger *trig, *trig2;
+	struct iio_prtc_trigger_info *trig_info;
+	mutex_lock(&iio_prtc_trigger_list_lock);
+	list_for_each_entry_safe(trig,
+				 trig2,
+				 &iio_prtc_trigger_list,
+				 alloc_list) {
+		trig_info = trig->private_data;
+		rtc_irq_unregister(trig_info->rtc, &trig_info->task);
+		rtc_class_close(trig_info->rtc);
+		kfree(trig->name);
+		kfree(trig_info);
+		iio_trigger_unregister(trig);
+	}
+	mutex_unlock(&iio_prtc_trigger_list_lock);
+	return 0;
+}
+
+static struct platform_driver iio_trig_periodic_rtc_driver = {
+	.probe = iio_trig_periodic_rtc_probe,
+	.remove = iio_trig_periodic_rtc_remove,
+	.driver = {
+		.name = "iio_prtc_trigger",
+		.owner = THIS_MODULE,
+	},
+};
+
+static int __init iio_trig_periodic_rtc_init(void)
+{
+	return platform_driver_register(&iio_trig_periodic_rtc_driver);
+}
+
+static void __exit iio_trig_periodic_rtc_exit(void)
+{
+	return platform_driver_unregister(&iio_trig_periodic_rtc_driver);
+}
+
+module_init(iio_trig_periodic_rtc_init);
+module_exit(iio_trig_periodic_rtc_exit);
+MODULE_AUTHOR("Jonathan Cameron <jic23@cam.ac.uk>");
+MODULE_DESCRIPTION("Periodic realtime clock  trigger for the iio subsystem");
+MODULE_LICENSE("GPL v2");